π++d→p+pbelow 21 MeV

Abstract

Absolute total and differential cross sections for the reaction sr+ + d -+ p+ p have been measured for pion energies from 3.7 to 20.5 MeV. A crossed-field velocity separator was used to enhance the purity of the pion beam, and a deuterated scintillator was used both as the target and to count the incident Aux. The total cross sections are 4.0 + 0.5, 4.4 + 0.2, 4.2 + 0.2, 4.2 + 0.2, and 4.8 + 0.3 mb for incident pion energies of 3.7, 5.0, 9.6, 15.2, and 20.5 MeV, respectively. The measured difFerential cross sections indicate the presence of p-wave strength at all energies studied and are in good agreement with recent measurements for the reaction n+ p~d + n' near threshold and a recent parametrization of the total and difFerential cross sections for the process. PACS number(s): 25.80.Ls, 25.10.+s

p-wave pion production from nucleon-nucleon collisions

“…Shown are d = 3 (red solid line), d = 0 (black dashed line), and d = −3 (blue dot-dashed line). The data are from Refs [53,54,55,56,57]…”

Effective Field Theory calculations of $NN\to NNπ$

“…where T is the N N T-matrix, s(p) ≃ (2m N + p 2 /m N ) 2 for the nonrelativistic nucleons and C is a model-dependent constant (up to higher order terms in p/m N ). Thus the whole momentum dependence of the contact term contribution is modelindependent, since it is fully determined by the product of the two Omnès functions for the 1 S 0 and 87,88,[112][113][114] best overall description of the differential cross sections and analyzing powers in the different N N → N N π channels. In particular, Fig.…”

“…Shown are d = 3 (red solid line), d = 0 (black dashed line), and d = −3 (blue dot-dashed line). The data are from Refs 87,88,[112][113][114].…”

The Beauty of Spin

“…That is to say, each energy value W , computed on the periodic lattice at some fixed values of m 1 , m 2 , gives rise to a certain momentum k. The scattering phase at this momentum and pion mass is given by Eq. (8). Fitting δ to the effective range formula Eq.…”